The specific aims of this research are to detect developmentally and functionally distinct polymorphic and monomorphic antigens on non-T, non-B mononuclear cells, granulocytes and vascular endothelial cells; to use the antibodies reacting with these antigens to isolate phenotypically marked subsets of these cells; and to determine functional characteristics of these subsets. Particular attention will be paid to alloantisera that appear to identify polymorphic antigens on cells with specialized functions with respect to the inheritance of the antigens they detect, the clinical circumstances in which these antibodies have arisen and the tissue distribution of the determinants. These studies may shed considerable light on the pathogenetic mechanisms involved in certain diseases and transplantation biology. Monoclonal antibodies will be used to identify the tissue specificity and ontogeny of monomorphic antigens and to isolate cells bearing these antigens for in vitro functional studies. We have produced a panel of 15 monoclonal antibodies that detect granulocyte, non-T, no-B mononuclear cells and endothelial cell antigens. With this panel, cell marker studies will be carried out pre and post transplantation at sequential intervals assaying the appearance and frequency of lymphocytes, monocytes, natural killer cells and dendritic cells in the peripheral blood, bone marrow and other tissues. These studies will influence our decisions regarding the use of monoclonal antibodies in the prophylaxis and/or treatment of various diseases and transplantation. These antibodies will also be used to examine individuals with immunodeficiency disorders and aging populations.